Could pneumatic tires soon become a thing of the past? Although they have served us well for over a century, both Michelin and Resilient Technologies have attempted to build a replacement: the non-pneumatic tire. Or as Michelin has dubbed it: the Tweel!
What is a Tweel?
Well, the name Tweel is a merger of the words tire and wheel. This is because the Tweel does not use a traditional wheel hub assembly. The Tweel concept was first announced by Michelin back in 2005. It’s structure is a solid inner hub mounted onto the vehicles axle, that is surrounded by polyurethane spokes. These spokes look similar to the ones found on bicycles. A sheer band is then stretched across the spokes, which forms the outer edge of the tire. It is the tension of the band and the strength of the spokes that replaces the air pressure used on traditional tires. When a vehicle drives over an obstacle, a sleeping policeman for example, the tread and shear bands give way as the spokes bend, before they quickly bounce back into shape.
Advantages over pneumatic tires
The biggest weakness of pneumatic tires is of course the constant potential of a puncture. With a bit of luck it will only immobilize the vehicle. If a tire happens to puncture on a motorway at the wrong moment it can have serious consequences. Punctures are also one of the biggest concerns for vehicles in combat.
Of course another problem with pneumatic tires is that depending on the air pressure the car will have more or less traction, which will have an influence on the car’s handling. Not everyone knows how to inflate their tires optimally.
Drawbacks of Tweels at this point in time
- Lack of adjustability
One of the biggest disadvantages of the Tweel is that once it has been manufactured, it cannot be adjusted. In this case if the car needed a different kind of setting, a whole new set of Tweels will be required. On the plus side Tweels are made with five times the lateral stiffness compared to pneumatic tires, enabling very responsive handling.
- Not as economic as pneumatic tires
Michelin are currently working on enabling the Tweels to be as fuel efficient as pneumatic tires. Currently they are within 5% of the rolling resistance and mass levels.
This could be one of the Tweels biggest downsides. Vibrations become considerate once a vehicle is driving above 50 mph, while causing a lot of noise. Also disturbing is the amount of heat the Tweels generate. Long distance journey with tweels would be very unpleasant unless these areas are improved upon.
Can the tweel really overcome all these drawbacks?
That all depends on the engineers at both Michelin and Resilient Technologies. Even Michelin admit they cannot see the Tweels replacing the traditional tire any time in the near future. However, they might have found a useful application for the tweels in the meantime. Their use makes sense on construction sites, especially since vehicles there move at slower speeds. The military is also working with Michelin to explore the Tweels potential. Only time will tell if they manage to establish themselves among consumers.